Lithium batteries, or batteries that contain metallic lithium, a lithium alloy, or a lithium ion, have relatively high energy and are used in many electrical devices. In many military and industrial applications, large and relatively high voltage rechargeable lithium batteries or cells are used. Many of these applications are critical. Therefore, the safety and operation of the lithium batteries is of vital importance. It is often desirable to test the battery design for overall performance and safety. One of the performance criteria is the ability of the battery or cell to release internal pressure without any violent venting. Generally, lithium batteries must be vented as a result of gases or pressure being formed due to the electrochemical reactions under certain load conditions and during charging. Testing procedures, such as Underwriter Laboratory Standards UL 1642, relating to the standard for safety for lithium batteries and abnormal charging tests have proven to be inadequate for many lithium batteries. Underwriter Laboratory standards call for subjecting the cell or battery to a 12-volt DC power supply, charging and overcharging the battery at a current rate three times the vendor's specification for a duration specified by the following formula: EQU Charging duration or time=(2.5.times.C)/(3.times.I)
Where,
C is the rated capacity of the cell, and PA1 I is the batteries specified charging current.
The Underwiter Laboratory standards test methods are not sufficient to cause many rechargeable lithium batteries or cells to vent. Accordingly, these batteries would be determined safe according to the prior standards, when they may not be. Therefore, there is a need for a new testing procedure that will more adequately test the lithium battery or cell to ascertain the safety of the lithium battery or cell. Ascertaining the safety of the lithium battery or cell design is critical in view of the military and specialized industrial applications to which the lithium batteries or cells are placed. Any failure of a lithium battery, in addition to the failure of operation, may also result in a risk of fire or explosion of the lithium battery or cell. Therefore, it is critical that the lithium battery or cell be adequately tested, particularly the vent, and deemed safe prior to deployment or use. Accordingly, there is a need for an apparatus and test method to assure the safety of lithium batteries or cells.